Universal method of rolling rails and a mill train for the same

ABSTRACT

A universal method of rolling rails and a mill train for the same comprises an edging rolling mill set anterior to or/and posterior to a universal rolling mill. The edging rolling mill consists of a first rail edging roll pass and a second edging roll pass containing a set of the pass designs so different as to have the radii to meet respective corners of the head and of the foot of the so-rolled rail made larger than those of the pass designs of the first edging roll pass. The second edging roll pass is operated in combination with the universal rolling mill so as to conduct rolling following the rolling operation of the universal rolling mill and the first edging roll pass.

United States Patent Ishibashi et al.

[ 51 Apr. 25, 1972 [54] UNIVERSAL METHOD OF ROLLING RAILS AND A MILLTRAIN FOR THE SAME [72] lnventors: Yoshiyuki Ishibashi; KanichiKishikawa,

both of Kitakyushu, Japan [73] Assignee: Nippon Steel Corporation,Tokyo, Japan [22] Filed: Dec. 2, 1969 [2!] Appl. No.: 881,379

[56] References Cited UNITED STATES PATENTS Primary Examiner-Milton S.Mehr Attorney-Wenderoth, Lind & Ponack ABSTRACT A universal method ofrolling rails and a mill train for the same comprises an edging rollingmill set anterior to or/and posterior to a universal rolling mill. Theedging rolling mill consists of a first rail edging roll pass and asecond edging roll pass containing a set of the pass designs sodifferent as to have the radii to meet respective corners of the headand of the foot of the so-rolled rail made larger than those of the passdesigns of the first edging roll pass. The second edging roll pass isoperated in combination with the universal rolling mill so as to conductrolling following the rolling operation of the universal rolling milland the first edging roll pass.

7 Claims, 8 Drawing Figures PATENTEDA R25|912 3, 657, 912

PRIOR ART PRIOR ART PRIOR ART YOSHIYUKI ISHIBASIII INVENTORS and KANICHIKISHIKAWA wmmwm ATTORNEY S PATENTEDAPR 25 I972 SHEET 20F 2 YOSHIYUKIINVENTOR ISHIBASHI and kanichi kishikawa BY 1! t r 1 ATTORNEY,-

UNIVERSAL METHODOF ROLLING RAILS AND A MILL TRAIN FOR THE SAMEBACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates in general to a method of rolling rails and the milltrain for the same, and more particularly to a method of rolling railsby a special edging rolling mill in combination with a universal rollingmill and a mill train for the same.

2. Description of the Prior Art Generally, rolling of rails is done bythe so-called rolling method of roll pass type, wherein rolling iscarried out with upper and lower horizontal rolls having pass designs.However, this rolling method requires a high level of operationtechnique; the pass designs used for the method are diflicult to designand manage; and products rolled by this method are not precise as toshape. Therefore, with the low rate of passing the specifications ofproducts of high precision, and because of low productivity of themethod, products are inevitably high-priced.

In order to solve such problems as mentioned above, the universalrolling mill method is gaining popularity. The universal rolling methodis fundamentally different from the above rolling method of the rollpass type. The former uses a universal rolling mill with the horizontalrolls and vertical rolls concentrating reduction on every part of theto-be-called material, particularly the upper surface and both sides ofthe part to be rolled into the head of the rail which will contactwheels, thus producing a rail having a head of good quality resultedfrom sufficient forging.

However, this method is so carried out that the material to be rolledinto a rail is several times reciprocally subjected to the universalrolling mill and edging rolling mill. However, particularly in the caseof rolling such products as rails that have the head and the footreduced greatly differently, even the rolling operation by this methodis impossible, for the following reason. When rolling the material to berolled into a rail by using the universal rolling mill, part of thereduction power put on the head and the foot of the rail works so as tomake them stretch in their. respective directions, and moreover they aresubjected to the reduction of the same rate, making the reduction of thehead greater than that of the foot. This causes a great difference inthe above stretched volume between the head and the foot. Even withrespect to the head of the rail, the stretched volume varies top tobottom. Subsequent to the universal rolling mill, therail is sent to theedging rolling mill which is equipped with the roll pass so designed asto put the same reduction rate to the head and the foot, but the passingof such to-be-rolled material as the rail I having the head and the footwith greatly different stretched volumes causes different reductionrates between these parts, thus causing such troubles as bending of theso-called products, these troubles making any further reciprocal rollingimpossible. Even if such rolling can be carried out, the corners of thehead and of the foot of the so-rolled rail will form an acute angle,which constitutes a fatal shortcoming of the prior art method. Thus, itis believed to be difficult to develop an effective and economicaluniversal rail rolling method.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a universal method of rolling rails, whereby the reciprocalrolling of rails is made possible by using an edging roll mill which canshift swiftly to a second edging rod for rolling the corners of the headand of the foot of the so-called rail so as to not form an acute angle.These corners are all formed by using, in addition to the normal passdesign, a second pass design with radii to cause the corners to be madelarger than those of the abovementioned normal pass design, whereby arail having a suffrciently forged head can be produced, thus solving theabovementioned problem of the universal rail rolling method which hasbeen in use.

Another object of the present invention is to provide a mill train forrolling rails of high accuracy in size and shape, which requires norolls of the roll pass type and which can be operated very easilycompared with the operation of the rolling method of the roll pass type.

In order to attain these objects, the present invention is developed inrelation to a method of rolling rails by using a rolling mill traincomprising a universal rolling mill, an edging rolling mill, a finishingrolling mill, etc., wherein said edging rolling mill is set anterior toand/or posterior to said universal rolling mill, and said edging rollingmill consists of a first rail edging roll pass (hereafter called the:first edging roll pass") and a second roll pass (hereafter called thesecond edging roll pass) containing a set of the pass designs sodifferent as to have radii to form respective corners of the head andthe foot of the so-rolled rail larger than those of the pass designs ofthe first edging roll pass. The rolling operation is carried out byusing the combination of the second edging roll pass with the universalrolling mill following the rolling operation using the universal rollingmill and the first edging roll pass.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plan sketch of theuniversal rail rolling mill train conventionally in use.

FIG. 2 shows a plan perspective, with partial sections rotated, of therolling operation as it is carried out by the universal rolling mill u,the edging rolling mill E and the finishing rolling mill F shown in FIG.1.

FIG. 3 shows the progress of the material the universal rolling millshown in FIG. 2.

FIG. 4 shows the progress of the material as it is rolled by the edgingrolling mill shown in FIG. 2.

FIGS. SA-C show universal rail rolling mill trains according to thepresent invention.

FIG. 6 shows the progress of the material as it is rolled ac cording tothe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The following is an explanationof the present invention in comparisonwith the conventional rollingmethod which has such problems as mentioned above. I

FIGS. 1 and 2 show the conventional type of the universal mill train forrolling rails, in which a rough-rolled billet having a symmetricalsection which has passed through the blooming rolling mill V1 and thebreakdown rolling mill V2, is several times reciprocally subjected tothe universal rolling mill to and the edging rolling mill E. AS isknown, the universal rolling mill u has the horizontal rolls 6 and 7 toroll the web of the sorolled rail from above and below and the verticalrolling mills 4 and 5 to roll the head 1 and the foot 2 of the so-ro1ledrail from both sides (since FIG. 2 is a plan diagram with sections ofthe rolls and rails rotated, the horizontal rolls appear vertical, andvice versa); and the edging rolling mill E has the upper and lowerhorizontal rolls 8 and 9 with pass designs to edge the material whichhas passed through the universal rolling mill 14. After having passedthrough the edging rolling mill E, the material is sent to the finalfinishing rolling mill which is indicated with the sign F. In FIG. 1,the line with the arrows shows the passage of the to-be-rolled material;10 indicates the motor of each mill.

Using FIGS. 3 and 4, the rolling of the material during the reciprocatedsubjection to the universal rolling mill u and the edging rolling mill Eafter having passed through the breakdown rolling mill V2, is explained,as follows:

Having passed through the breakdown rolling mill V2, the material issent to the universal rolling mill u. In this mill, the positions, atthe first pass, of the vertical rolls 4 and 5 and the upper and lowerhorizontal rolls 6 and 7 are indicated respectively with 4-1, 5-1, 6-1and 7-1, as they are reducing respectively the head 1, and foot 2 andthe web 3. Then, the material is sent to the edging rolling mill E, asshown in FIG. 4; and the positions, at the first pass, of the horizontalrolls 8 and 9 are indicated respectively with 8-1 and 9-1.

as it is rolled by The material continues to be reciprocally subjected,as prescribed, to the universal rolling mill u and the edging rollingmill E; and, at the third pass, respective rolls of the universalrolling mill u are positioned at 4-3, 5-3, 6-3 and 7-3, and thehorizontal rolls 8 and 9 of the edger rolling mill E are positionedrespectively at 8-3 and 9-3. In the figure, rolling actions are shown inthree passes. In actual cases, however, they are sometimes carried outfive to seven or more passes. v

In this case, the upper and lower horizontal rolls and the verticalrolls of the universal rolling mill u are so designed as to form anydesired cross-section. Therefore, no acute angle is produced on thecorners of the head 1 and the foot 2. However, the horizontal rolls 8and 9 of the edging rolling mill E have pass designs, so they areadjustable only in the upward and downward direction. This causescertain parts of the head I and the foot 2 not to meet the pass designsas rolling operation progresses. That is because, after the fifth passof the head 1 of the so-rolled rail, there is produced a difference ofAH in reduction from the first pass, causing the head 1 of the sorolledrail, at least its corner A, to leave and be free from contact by thepass designs of the horizontal rolls of the edge rolling mill.

After being finished, corner A should have the prescribed radius R],But, since it has not been contacted by the pass designs of the edgerolling mill, the corner tends to have a shape of an acute angle; andresidual stress is produced there due to insufficient forging. The head1 of the so-rolled rail is subjected to concentrated reduction by trainwheels, and therefore it should be subjected to sufficient forging bythe rolling mill prior to such concentrated reduction, and should havesuch a profile as to stand actual severe use. For this purpose, therehas been known the availability of the tandem rolling mill train havinga number of universal rolling mills and edging rolling mills arrangedalternately. But this sort of the rolling mill train is too expensive tobe commercially practicable.

Also on the corner B of the foot 2 there will be seen the samesituation. That is to say, even if the pass design is so constructed asto produce the prescribed curve rate on said corner B, as the rollingoperation progresses, say, at the third pass, the difference of Aoccurs, causing the corner to not be contracted by the pass design. Saidcorner B of the foot 2 of the so-rolled rail'should have its radiusdesigned so as not to damage rail sleepers or gather rust. Once anundesirable profile is formed at that stage, it is impossible tocorrectit by the finishing rolling mill F.

In order to solve such problems as mentioned above taking place inrolling rails by reciprocal subjection to the universal rolling mill andthe edging rolling mill, the present invention provides, in addition tothe abovementioned edging roll pass, a second edging roll pass in theedging rolling mill E. This causes, at the latter stage of rollingoperation, the prescribed radiuses for respective corners of the headand the foot of the so-rolled rail to be formed by the other edging rollpass.

As mentioned above, the present invention is characterized by thearrangement of a blooming rolling mill, a universal rolling mill, anedging rolling mill, a finishing rolling mill, etc., and the rollingmethod using such arrangement of the rolling mills, wherein the edgingrolling mill set near anterior and/or posterior to the universal rollingmill is provided with a second edging roll having such pass design as toform the curve rates prescribed to meet the corners of the head and thefoot of the so-rolled rail, and the second edging roll is so designed asto move in a direction perpendicular to the rolling line.

The following is to explain the present invention concretely using thepreferred examples shown in the drawings:

In FIG. 5, V1, V2 and u indicate respectively a blooming rolling mill, abreakdown rolling mill and a universal roughing rolling mill; El and E2indicate respectively a first edging roll and a second edging roll, ofwhich pass designs are different one from the other; and F indicates auniversal finishing rolling mill. In the rolling mill train shown inFIG. 5A, a steel billet is bloomed and roughed respectively by theblooming rolling mill V1 and the roughing rolling mill V2, and thensubjected reciprocally in several passes to the edging roll E1, and theuniversal roughing rolling mill u. In the latter stage of rollingoperation, are employed the universal rolling mill u and the secondedging roll E2, which replaces the edging roll E1 on the rolling line bymoving the edging rolls El and E2 in the direction indicated by thearrow. FIG. 5B shows a rolling mill train, in which the first edgingroll E1 and the second edging roll E2 having different pass designs onefrom the other, are arranged posterior to the universal roughing rollingmill u. FIG. 5C shows a rolling mill train, in which the first edgingroll El and the second edging roll E2 and another set of such rolls Eland E2 having different pass designs one from the other are arrangedrespectively anterior and posterior to the universal rouging rollingmill :4.

The rolling method by using the rolling mill trains shown in FIG. 5B and5C, is the same as that by using the rolling mill train shown in FIG.5A. But when using the rolling mill train shown in FIG. 5C, there areseen such advantages that while either of the edging rolls in used, theother acts as a guide, and while either of them is replaced after beingworn out by a long period of use, the other can carry out rollingsmoothly and perfectly. FIG. 6 shows the enlarged view of the rollingoperation carried out in the abovementioned situation. In the figure,the to-be-rolled material has been reduced by two passes through theuniversal rolling mill u and the edging roll El so as to have a certaincross-section, which process is the same as that used in theconventional method. In this case, as mentioned above, the corner A ofthe head 1 and the corner B of the foot 2 of the so rolled rail form anacute angle to some extent.

In the latter stage of rolling operation after the above mentioned, saidedging roll E1 is made to move out of the rolling line, and instead ofthis roll, the second edging roll E2 is set on the rolling line, bymovement of the edging rolling mill E itself or otherwise.

In comparison with the pass design of the edging roll E], that of theedging roll E2 is smaller in the height of the part corresponding to thehead 1 of the so-rolled rail and also in the thickness of the partcorresponding to the foot 2; and also the second edging roll E2 has passdesigns with the radius R1 for the corner A of the head I of theso-rolled rail and with the radius R2 for the corner B of the foot 2.The material to be rolled into a roll is made to pass, one or two times,through the universal rolling mill u and the second edging roll E2.Thus, by these passes, the corner of the head and the corner of the footof the so-rolled rail will be formed into the desirable profile havingthe prescribed radii R1 and R2. The so-rolled rail is then subjected tothe final finishing rolling mill F to become a final product. The radiusR1 of the corner A of the head must be made larger than the radiusformed by the edging roll E1 of the former edging rolling mill. This isparticularly to forging the corner of the rail which will be subjectedmost severely to mechanical impact.

As will be apparent from FIG. 6, in the universal mill u, the portionsof the rail material other than the side surfaces (indicated by dottedlines in FIG. 6) of the head 1 and the foot 2 are subjected to rollingreduction by the vertical rolls 4 and 5 and by the upper and lowerhorizontal rolls 6 and 7. By this reduction, (pass 6] in FIG. 6) Theside surfaces of the head I and the foot 2 swell out to some extent.

The rail material rolled by the aforesaid universal mill is then reducedby the first pair of rolls E1 of the edging mill E. The edging rolls Elreduce the material excluding the top surfaces of the head 1 and thebottom surface of the foot 2 (respectively indicated by dotted lines inFIG. 6,) thus reducing the sides of the head 1 and foot 2 which have notbeen subjected to reduction by the previous passage through theuniversal mill u (pass E-l 1 in FIG. 6).

By performing several passes through the universal mill u and the edgingmill E employing the edging rolls El while narrowing the intervalbetween the respective opposed rolls, both mills u and E cooperate incomplementary reduction of the material into an intended railconfiguration. Subsequent passes through it and E1 are represented by6-2 and El-2 in FIG. 6.

Following the above described rolling, the universal mill u and thesecond pair of edging rolls E2 of the edging mill E are used forsubsequent rolling. In FIG. 6 these passes are represented by 6-3 andE2-1, respectively. In this subsequent rolling, the edging mill E withrolls E2 mainly reduces the sides of the head 1 and the foot 2 whichrespectively include the corners A and B shown in FIG, 4. The portionsof rolls E2 which contact corners A and B are so formed that the radiusof curvature RI on the border between the top surface of the head 1 andeach of the side surfaces thereof and the radius of curvature R2 on theborder between the bottom surface of the foot 2 and each of the sidesurfaces thereof are larger than the respective radii of rolls E1.Therefore, the corners A and B of the rail can be reduced sufficientlyto be rounded and forged to a substantially increased degree.

As mentioned above, by employing the rolling mill train and the rollingmethod according to the present invention, it is possible to producerails of high accuracy in size with a single universal rolling mill andan edging mill which are inexpensive. The quality of the so-rolled railis as good as or even better than that of rails which are produced bysuch wellknown, but expensive rolling equipment as the tandem rollingmill.

We claim: 1. In the method of rolling rails by employing a universalrolling mill and an edging rolling mill, the improvement of theuniversal rail rolling method which comprises:

rolling a roughly rolled billet into a rail by reciprocation thereofthrough said universal rolling mill and a first pair of edging rolls ofsaid edging rolling mill, the progress of the reciprocative rollingcausing the corners of each of the head and foot of the rail to becomeunaffected by the roll pass of said edging rolling mill,

subsequently replacing said first pair of edging rolls of said edgingrolling mill by a second pair of edging rolls by shifting the latterrolls to the rolling line, said second pair of edging rolls having acontour such that the portions thereof which meet the corners of each ofthe head and foot of said rail have larger radii than those of thecorresponding portions of said first pair of edging rolls, and againrolling the material subjected to the aforesaid reciprocative rolling,by the reciprocative passage through said second pair of edging rollsand said universal rolling mill, and

finally rolling the thus rolled material into a finished rail by afinishing rolling mill.

2. In a universal rail rolling mill train including a universal rollingmill and an edging rolling mill, a rail being formed by reciprocating aroughly rolled billet back and forth through said universal rolling milland said edging rolling mill; the improvement wherein said edgingrolling mill comprises a first pair of edging rolls and a second pair ofedging rolls, said pairs of edging rolls having portions formed tocontact the corners of the head and foot of said roughly rolled billetwhile being formed into said rail, said portions of said second pairs ofedging rolls have larger radii than said portions of said first pair ofedging rolls; and means mounting said pairs of edging rolls forselectively shifting one of said pairs into the path of rolling of saidrail and the other of said pairs out of said path.

3. The improvement claimed in claim; 2, wherein said edging rolling millis positioned anterior to said] universal rolling mill.

4. The improvement claimed in claim. 2, wherein said edging rolling millis positioned posterior to said universal rolling mill.

5. The improvement claimed in claim 2, wherein said edging rolling millis positioned anterior to said universal rolling'rnill, and furthercomprising a second edging rolling mil identical to the first edgingrolling mill positioned posterior to said universal rolling mill.

The improvement claimed in claim 2, wherein said mounting means slidessaid pairs of edging rolls in a direction perpendicular to said path.

7. The improvement claimed in claim 2, wherein said second pair ofedging rolls is dimensioned such that the part thereof contacting thehead of the rail is shorter and the part thereof contacting the foot ofsaid rail is thinner than the corresponding parts of said first pair ofedging rolls.

1. In the method of rolling Rails by employing a universal rolling milland an edging rolling mill, the improvement of the universal railrolling method which comprises: rolling a roughly rolled billet into arail by reciprocation thereof through said universal rolling mill and afirst pair of edging rolls of said edging rolling mill, the progress ofthe reciprocative rolling causing the corners of each of the head andfoot of the rail to become unaffected by the roll pass of said edgingrolling mill, subsequently replacing said first pair of edging rolls ofsaid edging rolling mill by a second pair of edging rolls by shiftingthe latter rolls to the rolling line, said second pair of edging rollshaving a contour such that the portions thereof which meet the cornersof each of the head and foot of said rail have larger radii than thoseof the corresponding portions of said first pair of edging rolls, andagain rolling the material subjected to the aforesaid reciprocativerolling, by the reciprocative passage through said second pair of edgingrolls and said universal rolling mill, and finally rolling the thusrolled material into a finished rail by a finishing rolling mill.
 2. Ina universal rail rolling mill train including a universal rolling milland an edging rolling mill, a rail being formed by reciprocating aroughly rolled billet back and forth through said universal rolling milland said edging rolling mill; the improvement wherein said edgingrolling mill comprises a first pair of edging rolls and a second pair ofedging rolls, said pairs of edging rolls having portions formed tocontact the corners of the head and foot of said roughly rolled billetwhile being formed into said rail, said portions of said second pairs ofedging rolls have larger radii than said portions of said first pair ofedging rolls; and means mounting said pairs of edging rolls forselectively shifting one of said pairs into the path of rolling of saidrail and the other of said pairs out of said path.
 3. The improvementclaimed in claim 2, wherein said edging rolling mill is positionedanterior to said universal rolling mill.
 4. The improvement claimed inclaim 2, wherein said edging rolling mill is positioned posterior tosaid universal rolling mill.
 5. The improvement claimed in claim 2,wherein said edging rolling mill is positioned anterior to saiduniversal rolling mill, and further comprising a second edging rollingmil identical to the first edging rolling mill positioned posterior tosaid universal rolling mill.
 6. The improvement claimed in claim 2,wherein said mounting means slides said pairs of edging rolls in adirection perpendicular to said path.
 7. The improvement claimed inclaim 2, wherein said second pair of edging rolls is dimensioned suchthat the part thereof contacting the head of the rail is shorter and thepart thereof contacting the foot of said rail is thinner than thecorresponding parts of said first pair of edging rolls.